1. Field of the Invention
The present invention relates to a ratchet wrench, and more particularly to an assembled structure of the ratchet wrench which provides improved anti-uncoupling effects to make the wrench operate smoothly and integrally.
2. Prior Art
In accordance with the conventional ratchet wrench 10, as shown in FIG. 1, there is a containing hole 111 on a side of the plug joint portion 110 of the D-head 11 for housing a spring 112 and a ball 113. The ball 113 is located so that a portion thereof extends out from the mouth of the containing hole 111 at the side of the plug joint portion 110. The extending portion of the ball 113 elastically slides into a recess 122 of the socket 121 as the plug joint portion 110 is inserted into the socket 121 of a link rod 12 forming an elastic joint for preventing the link of the plug joint portion 110 and the link rod 12 from uncoupling. But, when the weight of a link rod 12 of larger size is so great as to override the backing force exerted on the back of the ball 113, or the ratchet wrench 10 is turned too fiercely, the ball 113 may be pressed inward to compress the spring 112 so that the link rod 12 uncouples with the plug joint portion 110 of the D-head 11. To overcome that problem, a manually displaceable ball 214 in a locking or releasing ratchet wrench, as shown in FIG. 2 and FIG. 3, was marketed later. The D-head 21 of the ratchet wrench 2 has a through-hole 210 formed axially through the center to connect with the containing hole 212 of the plug joint portion 211. The reversing disc 22 has a stepped central hole 221 with a larger diameter containing hole 222 formed in correspondence with the through-hole 210 for inserting a control rod 24 with a spring 23 therein. A tenon 223 is built upon the bottom side of the reversing disc 22. The control rod 24 has a ball seat 241 with a beveled push face 242 adjacent the bottom end thereof, corresponding to the containing hole 212 on the plug joint portion 211. The ball 214 is maintained in the containing hole 212 by punching a flange on the outer rim of the mouth of the hole 212 inwardly to prevent the ball 214 from falling out.
The tenon 223 on the bottom side of the reversing disc 22 is used to contact the top face of the D-head 21 for maintaining a space between them so that a cardioid spring 25 can move in that space freely along with the movement shift pin 224 of the reversing disc 22. When turning the reversing disc 22 to move the cardioid spring 25, one side of the cardioid spring 25 presses the tenon 223, as shown in FIG. 2, FIG. 3A and FIG. 3B, so that the reversing disc 22 is displaced to press the control rod 24 laterally and eccentrically with a side of the central hole 221, to cause the control rod 24 to hardly be able to slide in it due to high friction, even to bring about a locking-up phenomenon.
On the other hand, in assembling the control rod 24, the reversing disc 22, the cardioid spring 25, the loose ratchet 26 and so on, these need to be mounted at the same time, increasing the complexity of the installation. The loose ratchet 26 and the cardioid spring 25 are located in place, then the reversing disc 22 is installed by putting the shift pin 224 into the closed end of the cardioid spring 25, and twisting the reversing disc 22 to deform the cardioid spring 25 so that the central hole 222 overlaps on the through-hole 210 of the D-head 21, in order to plug the control rod 24 and the spring 23 in the holes 222 and 210. Finally, the ball 214 is retained in the containing hole 212 of the plug joint portion 211 and disposed in the ball seat 241 by punching a flange at the outer rim of the mouth of the containing hole 212 inwardly, to assemble the impelling head 20. Because installing the control rod 24 is so complex, especially to locate the cardioid spring 25, the installation of the impelling head is difficult and has high production cost. On the other hand, for retaining the impelling head 20, a snap ring 27 clamps on the ring groove 213 of the plug joint portion 211 of the D-head 21. Between the snap ring 27 and the head portion 2 there is a gap C. Due to the existence of the gap C, the impelling head 20 will sway. The gap C may be enlarged or reduced by machining errors. If the gap C is too small, the impelling head 20 will be clamped down. If the gap C is enlarged, the bigger the gap C is, the greater the shake of the impelling head 20 is, so that the percentage of defective wrenches is quite high. Therefore, controlling the size of the gap C has become a technical bottle-neck for manufacturers. And the reversing disc 22 of the impelling head 20 has a conic top face, as shown in FIG. 4, for pushing to turn the impelling disc 20 with he thumb of the user. But because the contacting surface of the reversing disc 22 is so slippery, the user has to exert a much greater force on the tip of the thumb in order to rotate the reversing disc 22.
Referring to FIG. 5, FIG. 6, FIG. 6A and FIG. 6B, another kind of conventional ratchet wrench is shown, in which the head portion 310 of the wrench 31 has many axial teeth 311 arranged on the inside wall. The D-head 32, the loose ratchet 33 and the cardioid spring 34 are mounted into the head portion 310 from one end. The reversing disc 35 is mounted from the other end so that the shift pin 351 at the bottom side of the reversing disc 35 inserts into the closed end of the cardioid spring 34. Then, the reversing disc 35 is secured to the D-head 32 to saddle the head portion 310 by a screw 37 and a washer 36. In this case, the D-head 32 and the reversing disc 35 cannot contact the head portion 310, otherwise they could not rotate in the head portion 310. As shown in FIG. 6A and FIG. 6B, a proper gap C has to be maintained between the D-head 32 or the reversing disc 35 and the head portion 310 respectively, and the size of the gap C is controlled by adjusting the bolt 37. Therefore, the bolt 37 has to be in a loose state for that purpose. In order to locate the bolt 37 in place and prevent it from loosening, the manufacturers usually employ one of the following methods:
1. Coating a Teflon layer on the outer surface of the bolt 37 to increase the tightness of the threaded connection, but it cannot retain the bolt 37 at a set tightness, especially in response to beating, colliding or falling down to the ground. The coated bolt 37 still loosens, or after undergoing adjustment many times, the Teflon layer on the coated bolt 37 peels off, losing the tightness effect.
2. Applying a bonding agent on the threaded section, a portion of the bonding agent will spread out to other places, to adhere to other parts like the cardioid spring 34, or the D-head 32 and the reversing disc 35, so that they cannot move normally. Once the bolt 37 is loosened from the bonding joint by striking during use, or during adjustment of the gap C, it requires the user to take care in loosening bolt 37, with frequent checks to prevent the gap C from becoming too great.
On the other side, for increasing the contacting area, the conic top surface of the reversing disc 35 is treated to have a roughened surface for increasing friction, but it stall requires the user to exert a high pressing force on the surface to distort the user's thumb for increasing the contacting area to assist in rotating the reversing disc 35. If carried out many times, under this state, the user's thumb will feel pain and become tired.